1. Field of the Invention
The present invention relates to a communication apparatus and a control method therefor, an information apparatus and a control method therefor, a communication system, and control programs for implementing the methods, and more particularly relates to a technology of processing information acquired through communication by a communication apparatus.
2. Description of the Related Art
Conventionally, portable information terminals (Personal Digital Assistant: PDA) have been developed as information apparatuses for assisting individual intelligence activities. A portable information terminal of this kind has a liquid crystal image display device mounted thereon and has a schedule book function, a memory book function, a telephone book function, and the like.
Among communication apparatuses, development of portable telephone terminals has been progressed, and a function of accessing Web (World Wide Web) pages is provided for recent portable telephone terminals. Conventional peripheral technologies related to portable telephone terminals like these portable information terminals and portable telephone terminals will be described below.
Optical Devices
Development of optical design and production technology has realized magnifying projection using a prism with a free curved surface, and optical devices that provide a large screen even with a small size. Further, by combining such optical devices with high-definition display devices such as microdisplays, small-sized displays with a wide view and high resolution have been made available. This kind of technology has been so far applied to HMDs (Head Mounted Displays) and so on.
High-resolution Display Devices
Development of liquid crystal display technology has realized small-sized and high-resolution displays. Particularly in LCoS (Liquid Crystal on Silicon) technology which mounts a liquid crystal material onto a CMOS back plane, a technology of forming high-density circuits in semiconductor manufacturing is applied to realize high resolution and high response speed.
Input Devices Using a Pressure Sensitive Element or the Like
Input devices using a pressure sensitive element or the like to detect a slight movement of a finger and realize pointing on a two dimensional plane, equivalent to a pointing device (mouse), and button clicking have been diffused.
These input devices are used as an embedded type of pointing button or an auxiliary button for scrolling with a mouse of a note-type PC (Personal Computer).
Miniaturized Computer Devices
Progress in semiconductor manufacturing technologies, semiconductor design technologies, and others have realized small-sized and energy saving computer devices having high performance and high throughput. Also, processors composed of a chip provided functions such as bus control, memory control, timer, etc. implemented by such computer devices have come to be widely distributed.
In addition, the appearance of SoC (System on a Chip) technology and the like has allowed a function, which was conventionally implemented by a combination of a plurality of semiconductor chips including AS (Application Specified) IC part, to be realized on a single semiconductor chip. Thus, not only reduction in volume, but also reduction in energy consumption, has been made possible.
Wide Area Wireless Communication Networks
Wide area wireless communication networks typically for PHSs (Personal Handy phone Systems) and portable telephones have been installed, and portable telephone terminals have rapidly been diffused. This permits network communication without the restrictions of place. Communication bandwidth is also enormously becoming larger with the adoption of IMT-2000 specification.
Furthermore, i-mode service by NTT DoCoMo, EZ-Access by IDO, etc., although having some restrictions, enable access to Internet information services via their respective wide area wireless networks.
Portable Telephone Terminals
Recent development of mounting technology has achieved a great miniaturization of terminals for connection to portable telephone networks, which are wide area wireless communication networks provided by NTT DoCoMo and others.
Further, portable telephone terminals supporting i-mode service by NTT DoCoMo, EZ-Access by IDO, and the like have, though with some restrictions, are also capable of using Internet information services.
Furthermore, these portable telephone terminals are provided with a function of playing individually set melodies at the time of incoming calls. This function is called “ring tones”. Some portable telephone terminals have the capability of playing not only melodies of simple tones but also melodies of chords as ring tone melodies.
Still furthermore, with regard to IMT-2000 which is a next generation portable telephone system, a specification for mounting a user identification device referred to as UIM (User Identity Module), on a portable telephone terminal has been disclosed.
In order to cope with IMT-2000 portable telephone services, attempts have been made to enhance the capability of portable telephone terminals. Processors and memories to be mounted on portable telephone terminals have been reinforced, and further, memory capacities have been increased.
Text processing functions for e-mail etc. have been enhanced. Terminals with a predictive text input function such as T9 have been announced.
Browser software has advanced and enhanced in functions as well. Browsers for portable telephone terminals primarily have the capability of displaying pages for portable telephone terminals. These pages are described in WML (Wireless Markup Language) for WAP (Wireless Application Protocol) terminals, compact HTML for i-mode terminals, or XHTML Basic recommended by W3C.
Furthermore, portable telephone terminals equipped with a Java processing system are available on the market, which can execute programs downloaded from networks.
Portable telephones equipped with Bluetooth as an energy saving communication system, are also available on the market.
Download of Programs by Portable Telephone Terminals
Devices for downloading application programs, which operate on portable telephone terminals, from servers on networks are available. More specifically, such devices include specifications of i-applied by NTT DoCoMo, the Profile MIDP (Mobile Information Device Profile) of J2ME (Java 2 Platform, Micro Edition) employed by KDDI Group and J-PHONE Group for portable telephones, and so on.
This makes it possible to provide portable telephone terminals with functions that were not provided at the time of production of the portable telephone terminals.
In BREW specifications presented by QUALCOMM Inc. (US), it is possible to execute not only programs by Java processing systems but also programs described in C/C++.
Low Power Consuming Wireless Communication Systems
Progress in technologies of communication frequency control circuits, functions of adjusting radio wave strength, and others has realized fast communication systems with low power consumption. Many information apparatuses including portable telephone terminals and note type PCs (Personal computers) are coming to employ these communication systems.
Bluetooth is a typical low power consuming wireless communication system as described above. Particularly, Bluetooth SIG (Special Interest Group), who leads this Bluetooth system, specifies a combination of protocol stacks as a profile for each application using communication, for the purpose of spreading and promotion of the system, and in addition, secures the inter-connectability between Bluetooth-based devices. For example, according to “Dial-up Networking Profile” included in the Bluetooth specifications, a communication protocol, a communication procedure, etc. are specified for the case of using portable telephone terminals and the like as an Internet bridge.
Furthermore, in the Bluetooth specifications, a protocol (SDP: Service Discovery Protocol) and a profile (Service Discovery Application Profile) for a service discovery function are defined. Thus, on a Bluetooth network formed dynamically by wireless communication, the services that are provided by devices connected to the network can easily be found.
Still furthermore, in the Bluetooth specifications, a 48 bit data format referred to as BD_ADDR (Bluetooth Device Addresses; 48 bits) is used for addresses in order to identify individual devices.
External Memory Devices
Progress in semiconductor manufacturing technology and storage circuit systems etc. has greatly increased the storage capacity of memory devices. Particularly in recent years, standardized external memory devices have become available for use between various information apparatuses, and accordingly, a great deal of information can easily be exchanged via these external memory devices.
Internet Information Services
Various kinds of information are now available through the Internet. The information includes image data, text data, video and audio signals, etc., wherein the information can be distributed with a description system referred to as HTML (Hyper Text Markup Language). Also, connection providers called ISPs (Internet Service Providers) offer easy connection to the Internet via wide area communication networks such as telephone networks.
As these Internet information services have come to be provided via the wide area communication networks spread all over the world, it has been made possible to acquire a large amount of information in real time at any place.
In addition, i-mode by NTT DoCoMo permits using Internet information services even with portable telephone terminals with various hardware restrictions compared to PCs by adopting a subset of HTML referred to as compact HTML.
Small-sized Large-capacity Batteries
With the appearance of lithium ion batteries, lithium polymer batteries, etc., high power density batteries, in other words, small-sized large-capacity batteries have come to be available. This makes it possible to continuously use portable apparatuses for a long time.
Wired Data Communication Interfaces
Wired data communication interfaces represented by USB (Universal Serial Bus), IEEE1394, etc. are diffused as external interfaces for information apparatuses, particularly for PCs.
Encryption Technology
Methods of secret and secure data communication with encryption algorithms are established. In general, encryption algorithms can be categorized into a symmetrical key system using the same key information for encryption and decryption, and an asymmetrical key system using different key information for encryption and decryption. The both systems adopt a DES (Data Encryption Standard) encryption system, an RC4 encryption system, an RSA (the initials of the three developers': Rivest Shamir Adleman) encryption system, and so on. Also, it is possible to sign information or confirm it, using an asymmetrical encryption system (public key encryption system).
Secure Communication Technology
As a protocol that provides security in communication such as Web access with HTTP, SSL (Secure Socket Layer) was presented by Netscape Inc. (USA), and has been used in various kinds of software including the browser software by them. SSL is positioned above TCP/IP (Transmission Control Protocol/Internet Protocol) and below an application protocol such as HTTP (Hyper Text Transfer Protocol) or FTP (File Transfer Protocol), etc., providing the functions of server authentication, encryption of communication data, and client authentication (optional).
As a system that provides security in wireless communication, WTLS (Wireless Transport Layer Security) is defined by a WAP Forum as a part of WAP (Wireless Application Protocol). This is designed on the basis of SSL, and provides almost the same functions as those of SSL, including data integrity, encryption, terminal authentication, etc.
As a method that provides an authentication function in communication, the CHAP (Challenge-Handshake Authentication Protocol) system defined as RFC1334 is known. This system is primarily used in PPP (Point-to-Point Protocol: defined by RFC1661).
By using various peripheral technologies as described above, it has been realized that portable terminals have multi functions, including communication functions etc., and are smaller and more portable.
Conventional portable telephone terminals, however, have been forced to have a small display screen for their portability, which has sometimes made it difficult to display various contents extensively distributed on the Internet.
In addition, using optical magnification systems for a better screen displaying has caused a mismatch with the operating systems of conventional portable telephone terminals to make the browsing of contents difficult.